User documentation should include a timestamp and/or svn revision number

Details

Description

In order to easily identify when a set of documentation was generated, it would be useful to add a timestamp, and possibly the svn revision at which the documentation was generated, to the output. One approach would be to replace a token in either the input files or final output with the appropriate information using Ant. This may not work for PDFs, in which case the timestamp may need to be inserted at the intermediate XSL-FO stage.